style fixes suggested by @ildus

Author: funbringer

testgres/node.py

@@ -813,7 +813,7 @@ def psql(self,
 dbname=None,
 username=None,
 input=None,
-**kwargs):
+**variables):
 """
 Execute a query using psql.
 
@@ -823,7 +823,7 @@ def psql(self,
 dbname: database name to connect to.
 username: database user name.
 input: raw input to be passed.
-**kwargs: variables to be set before execution.
+**variables: vars to be set before execution.
 
 Returns:
 A tuple of (code, stdout, stderr).
@@ -854,7 +854,7 @@ def psql(self,
 ] # yapf: disable
 
 # set variables before execution
-for key, value in iteritems(kwargs):
+for key, value in iteritems(variables):
 psql_params.extend(["--set", '{}={}'.format(key, value)])
 
 # select query source